In 2012, PAG completed a report on groundwater use near shallow groundwater areas in eastern Pima County. The report includes totals of the number of exempt and non-exempt wells, drilling histories and water production estimates. We found that a one mile buffer around the Cienega-Davidson shallow groundwater system contains 29 non-exempt wells and 355 exempt (private low-water use) wells. PAG defined this system to contain upper and lower Cienega Creek, Davidson Canyon, Barrel Canyon, Gardner Canyon, and Agua Verde-Posta Quemada. Each area has unique well histories and groundwater level trends. Overall, the total number of exempt wells drilled in the buffered areas has steadily increased since 1990. PAG, in coordination with Pima County, has monitored groundwater and surface water in the Cienega Creek Natural Preserve (lower Cienega Creek) since 1989, thereby providing over three decades of water resource information. As a result, the quantity and quality of water resource data for lower Cienega Creek is dramatically better than that available for many other parts of the Cienega Valley. Riparian habitat and well owners, alike, rely on shallow groundwater resources.
Pima County conducted a 2013 analysis of long term water level trends by Pima County using PAG data among additional sources. This report shows a decline of most water-related parameters monitored in the Preserve. From 1993-2011, precipitation showed a declining trend in the winter, but no trend in the summer. During the same period, streamflow declined by approximately 50% with the most significant decline during June, which is a critical period for aquatic plants and animals each year. The extent of surface flow declined from a high of 9.5 miles (1984-1996), to a low of 1.24 miles in June of 2012. These trends cause researchers in the region to be concerned about the prospects for long term health of the aquatic and riparian system of Cienega Creek.
Collaborative presentation from the Science in the Sonoita Plains Symposium in June 2013 regarding both of the above topics.